Imaging Coulomb islands in a quantum Hall interferometer

B. Hackens (1) , F. Martins (1) , S. Faniel (1) , C. A. Dutu (1) , Hermann Sellier (2) , Serge Huant (3) , M. Pala (4) , L. Desplanque (5) , X. Wallart (5) , Vincent Bayot (3)

1 DICE - MLG - Dispositifs Intégrés et Circuits Electroniques Machine Learning Group
2 NEEL - QuNES - Nano-Electronique Quantique et Spectroscopie
3 NEEL - NOF - Nano-Optique et Forces
4 IMEP-LAHC - Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'Hyperfréquences et Caractérisation
5 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

In the quantum Hall regime, near integer filling factors, electrons should only be transmitted through spatially separated edge states. However, in mesoscopic systems, electronic transmission turns out to be more complex, giving rise to a large spectrum of magnetoresistance oscillations. To explain these observations, recent models put forward the theory that, as edge states come close to each other, electrons can hop between counterpropagating edge channels, or tunnel through Coulomb islands. Here, we use scanning gate microscopy to demonstrate the presence of QH Coulomb islands, and reveal the spatial structure of transport inside a QH interferometer. Locations of electron islands are found by modulating the tunnelling between edge states and confined electron orbits. Tuning the magnetic field, we unveil a continuous evolution of active electron islands. This allows to decrypt the complexity of high-magnetic-field magnetoresistance oscillations, and opens the way to further local-scale manipulations of QH localized states.

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

B. Hackens, F. Martins, S. Faniel, C. A. Dutu, Hermann Sellier, et al.. Imaging Coulomb islands in a quantum Hall interferometer. Nature Communications, 2010, 1, pp.39. ⟨10.1038/NCOMMS1038⟩. ⟨hal-00709461⟩